uvc_video_suspend

Ahora vamos a estudiar uvc_video_suspend:
/* --------------------------------------------------------------------------
 * Suspend/resume
 */

/*
 * Stop streaming without disabling the video queue.
 *
 * To let userspace applications resume without trouble, we must not touch the
 * video buffers in any way. We mark the device as frozen to make sure the URB
 * completion handler won't try to cancel the queue when we kill the URBs.
 */
int uvc_video_suspend(struct uvc_streaming *stream)
{
    if (!uvc_queue_streaming(&stream->queue))
        return 0;

    stream->frozen = 1;
    uvc_uninit_video(stream, 0);
    usb_set_interface(stream->dev->udev, stream->intfnum, 0);
    return 0;
}


Ahora voy a ir comentándolo para hacerlo más legible:
/* --------------------------------------------------------------------------
 * Suspend/resume
 */

/**
 * uvc_video_suspend - Stop streaming without disabling the video queue.
 * @stream: the stream that will be suspended
 *
 * To let userspace applications resume without trouble, we must not touch the
 * video buffers in any way. We mark the device as frozen to make sure the URB
 * completion handler won't try to cancel the queue when we kill the URBs.
 */
int uvc_video_suspend(struct uvc_streaming *stream)
{
    if (!uvc_queue_streaming(&stream->queue))  // if queue is STREAMING
        return 0;

    stream->frozen = 1;  //  uvc_video_device knowns if it's frozen or not
    uvc_uninit_video(stream, 0);  //  it will kill all URBs and free them
        //  it will alternate to the 0 alternative setting
    usb_set_interface(stream->dev->udev, stream->intfnum, 0);
    return 0;
}

No es muy complejo, pero es curioso que exista una alternativa de configuración número 0 que se use en este caso.